Only recently having ‘escaped’ from that phase myself, I do not have any of my own
I do consider myself to be one of those kids that’d try to find my way around potential blocks, just to see if I could do it. Nothing is as enticing as someone saying:“you can’t” In this day and age it’s virtually impossible to keep people from the internet if they really want to get on it. Especially teens have this insatiable urge to get their online high. Unless you plan on keeping them in Faraday cage, there’s very little you can do about it.
From personal experience I can say I’m glad my parents raised me well enough to evaluate ‘stuff’ on the web adequate and act accordingly.
Let’s say you do get this tracker, then they just enable communications only when and if the tracker is off, or there’s nobody nearby to notice. Then they continue using whatever it is you’d rather not have them use without any supervision or guidance.
The alternative would be to talk to them about why you’d rather not have them use it (that much/yet/all the time). I know, they don’t like talking, but I personally prefer a well argumented reason over a dictatorship of:“you can’t and I’m gonna take it from you. Why? 'Cause I say so, that’s why”. I know that might be your good right as a parent, but I’m much more willing to oblige if it’s reasonable.
I know a couple of kids that were being raised rather strict with ‘no violence games’ and stuff like that. Guess who was playing those things when their parents weren’t around… And since it couldn’t be discussed there was no supervision at all, or guidance for that matter. And that was in a time where you needed a physical desktop, which is hard to hide. You can stick a modern cellphone almost anywhere you like without it being noticed easily.